Search not working

We have just installed Omeka on our PROD server; all is working well in DEV. However, we are having issues with searches from the home page in PROD (/search) not returning expected results. All is working OK from the /items/browse page in PROD.

The problem also seems to be restricted to those records which were imported. Records which were added manually are not affected. And if we edit an imported record, the edited fields will show up in the search results, but not the others. Strangely, if I add some extra words to a title on an imported record, I can search on those extra words, but not on the original title.

Any advice?

Have you tried reindexing? If not, go to Settings -> Search and hit the index button and see if that improves results.

Yes, tried that to no effect. It looks like some words in the titles are searchable, and some not

Further info: if I change the words in a title that aren't searchable e.g. "pen" to "pens", "deakin" to "deakins", I can now search on those words. However, if I revert them back to the original, they are no longer searchable.

The pen/pens difference might be a MySql thing, where 3 letter words don't get indexed. That doesn't explain the deakin/deakins difference, though. If I remember right, though, if a word appears often enough, the db will ignore it in the search.

Sadly, this is moving into some territory about db indexing that goes beyond what I know a lot about.